A multi-institutional Clinical Core Unit (CCU) was established during the first five years of the Massachusetts ADRC and will continue during years 06 to 10. The three Units are at BAH, MGH, and UMMC. The overall goals of the CCU are to examine, diagnose, and enroll into the ADRC Patient Registry men and women with AD and related dementias , and health control subjects. An associated goal is to characterize the neurological, psychiatric, and neuropsychological features of AD across all stages of illness. The clinical experience at each Unit stimulates and supports new research initiatives, and enhances research productivity. In order to accomplish these goals, subjects are examined at one of the three clinical units; demographic and diagnostic information on all subjects are entered into the joint ADRC central Patient Registry. Standardized data are collected in each Unit on aspects of the clinical history of dementia, features of the neurological examination, results of cognitive tests, and laboratory diagnostic tests. These data are collected in a uniform manner at each of the three Units and maintained in separate but compatible databases. In order to track the course of illness, neurological and psychiatric examinations are repeated every six months; cognitive tests are performed every twelve months. Patients with AD are referred to specific research projects depending upon informed consent and the inclusion and exclusion criteria of each project. Patients with AD and control subjects are encouraged to sign a brain donation form indicating intent for postmortem examination.